21133745 has 8 divisors (see below), whose sum is σ = 25612200. Its totient is φ = 16739200.

The previous prime is 21133733. The next prime is 21133747. The reversal of 21133745 is 54733112.

It can be written as a sum of positive squares in 4 ways, for example, as 10784656 + 10349089 = 3284^2 + 3217^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21133745 - 2¹⁰ = 21132721 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21133747) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20420 + ... + 21429.

It is an arithmetic number, because the mean of its divisors is an integer number (3201525).

Almost surely, 2^21133745 is an apocalyptic number.

It is an amenable number.

21133745 is a deficient number, since it is larger than the sum of its proper divisors (4478455).

21133745 is a wasteful number, since it uses less digits than its factorization.

21133745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41955.

The product of its digits is 2520, while the sum is 26.

The square root of 21133745 is about 4597.1453098635. The cubic root of 21133745 is about 276.4768806963.

Adding to 21133745 its reverse (54733112), we get a palindrome (75866857).

The spelling of 21133745 in words is "twenty-one million, one hundred thirty-three thousand, seven hundred forty-five".